diff --git a/packages/skills/tests/test_toolbox_registry.py b/packages/skills/tests/test_toolbox_registry.py
index c05126b..e3a9409 100644
--- a/packages/skills/tests/test_toolbox_registry.py
+++ b/packages/skills/tests/test_toolbox_registry.py
@@ -7,6 +7,7 @@
 
 from __future__ import annotations
 
+import pytest
 from ww_agents import SPECS
 from ww_skills import TOOLBOX, get_tool
 
@@ -105,3 +106,11 @@ def test_get_tool_resolves_known_and_unknown() -> None:
     assert get_tool("brainstorm") is TOOLBOX["brainstorm"]
     assert get_tool("worldbuilding") is TOOLBOX["worldbuilding"]
     assert get_tool("does-not-exist") is None
+
+
+def test_toolbox_registry_is_read_only() -> None:
+    # CR-H7：注册表是单一真相源，运行时变异（注入/删除）须 fail-fast（冻结为 MappingProxyType）。
+    with pytest.raises(TypeError):
+        TOOLBOX["injected"] = TOOLBOX["brainstorm"]  # type: ignore[index]
+    with pytest.raises(TypeError):
+        del TOOLBOX["brainstorm"]  # type: ignore[attr-defined]
diff --git a/packages/skills/ww_skills/toolbox_registry.py b/packages/skills/ww_skills/toolbox_registry.py
index 534a441..05a07c0 100644
--- a/packages/skills/ww_skills/toolbox_registry.py
+++ b/packages/skills/ww_skills/toolbox_registry.py
@@ -16,6 +16,10 @@
 
 from __future__ import annotations
 
+from collections.abc import Mapping
+from types import MappingProxyType
+from typing import Final
+
 from ww_agents import SPECS
 from ww_agents.schemas import (
     BlurbResult,
@@ -67,7 +71,7 @@ _SOURCE_TEXT_FIELD = InputField(
 
 
 # 创作工具箱注册表：key → 描述符。15 条（legacy 3 + 新 8 + Scope B 4：续写/扩写/降AI/拆书）。
-TOOLBOX: dict[str, GeneratorTool] = {
+_TOOLBOX_BY_KEY: dict[str, GeneratorTool] = {
     # ---- legacy（spec=None，前端走 legacy_route 跳现有页面）----
     "worldbuilding": GeneratorTool(
         key="worldbuilding",
@@ -243,6 +247,10 @@ TOOLBOX: dict[str, GeneratorTool] = {
     ),
 }
 
+# MappingProxyType：只读视图，运行时 `TOOLBOX[x]=...` / `del TOOLBOX[x]` 抛 TypeError（单一
+# 真相源不可被污染；`Final` 仅静态检查、挡不住运行时变异，故须冻结成只读 Mapping）。
+TOOLBOX: Final[Mapping[str, GeneratorTool]] = MappingProxyType(_TOOLBOX_BY_KEY)
+
 
 def get_tool(key: str) -> GeneratorTool | None:
     """按 key 取生成器描述符；未知 key → None（端点据此返 404）。"""